Sections 7.1, 7.2: Sums, differences, products of polynomials CHAPTER 7: POLYNOMIALS

Transcription

1 Sections 7.1, 7.2: Sums, differences, products of polynomials CHAPTER 7: POLYNOMIALS

2 Quiz results Average 73%: high h score 100% Problems: Keeping track of negative signs x = + = + Function notation f(x) ~ y: the result of the input x is the input Retakes can be done up to 11 AM Oct. 11

3 Sum The result of adding The sum of two positive values is a positive ii The sum of two negative values is a negative When the values are different signs Find the difference Use the sign of the one with the larger absolute value

4 Difference Subtraction ti Needs to be done in order from left to right Subtract a negative value is the same as adding a positive Suggest you change signs of terms that are subtracted and use adding rules

5 Product The result of multiplication li of factors Product of two positives is positive Product of two negatives is positive If signs are opposite, the product is negative

6 Term A constant, t a variable or a product of a constant and one or more variable factors Terms are separated from one another by addition Subtraction in an expression or equation needs to be interpreted t as adding a negative term: Change its sign and use adding rules.

7 Monomial Single term May be product of a constant and one or more variables Variables may be raised to powers (exponents) Absence of a numeric constant implies the constant is 1

8 Polynomial Monomial or sum of monomial terms Named by number of terms Binomial: 2 Trinomial: 2

9 Polynomial degree The greatest t exponents in any term Add up the values of the exponents in each term 4x 3 y 2 +2x 2 y 2 +9xy 3 1 st term: 5 th degree 2 nd term: 4 th degree 3 rd term: 4 th degree Fifth degree polynomial

10 Terms are made of factors Numeric factor: Coefficient i Variable factors represented by letters

11 Like Terms Have exactly the same variable set Combine the coefficients (numeric factors) by addition i Recall that the term has a sign Positive Negative Combine by addition rules

12 Quadratic expression or function Second degree polynomial l f(x) = 2x 2 + 4x 3 Recall f(x) is the function, equivalent to the output x is the input: example x=3 f(3) = 2(3) 2 + 4(3) 3 = 2(9) = 27

13 Quadratic function Graph is called a parabola 30 f(x) Vertex: 10 this has minimum value Axis of symmetry 0 Some open downward Have maximum value x

14 Cubic function Graph is a serpentine shape May have horizontal line that crosses graph in more than one place

15 Adding functions f(x) = 2x 2 + 4x 3 g(x) = 3x 2 + 9x 7 (f+g)(x) = 2x 2 + 4x 3 3x 2 + 9x 7 Add like terms: watch the signs!! Do it vertical, not on one line 2x 2 + 4x 3 + x 2 + 9x 7 x 2 +13x 10

16 Subtracting functions f(x) = 2x 2 + 4x 3 g(x) = 3x 2 + 9x 7 (f g)(x) ) = 2x 2 + 4x 3 ( 3x 2 + 9x 7) Change every sign of function being subtracted!! Then add, watching signs Do it vertical, not on one line 2x 2 + 4x x 2 9x+ 7 5x 2 5x + 4

17 Multiplying monomials (finding products) Multiply numeric coefficients Combine exponents on like variables x 2 x 3 = Write factors without exponents to see what the exponent means x x x x x = x 5

18 Multiplying polynomial by monomial 2(3+5) = 2(8) = 16, right? Distribute multiplication over addition 2(3) +2(5) = = 16, same thing 2x(3x 2 + 5x) = 6x x 2 same thing with variables, just now terms are not like so you cannot combine them

19 Product of binomials (2+3)(2+5)=(5)(7)=35 (5)(7) 35 Multiply second factor by each term of first factor, then distributeib (2+3)(2+5)=2(2+5)+3(2+5)=14+21=35 With variables: (x+3)(x+5)= x(x+5)+3(x+5)= ( ) x 2 +5x+3x+15= Combine like terms: x 2 +8x+15

20 Product of binomials F.O.I.L. method Label terms Firsts, Lasts, Outsides, Insides F L F L (x+3)(x+5) O I I O Multiply: l draw line, write product, draw, write Firsts x 2 Outsides +5x Insides +3x Lasts +15 Combine like terms: x 2 +8x+15

21 Products of higher degree polynomials Be very methodical Draw line for the product of two terms Write the product of those terms Draw another line for product of terms Write the product of those two terms Etc: DO NOT DRAW ALL THE LINES AND GO BACK TO FIND THE PRODUCTS!! YOU WILL GET LOST!!